This invention relates generally to ambulatory heart monitoring method and apparatus. More specifically, it concerns ambulatory ECG data monitoring and recording method and apparatus having integral therewith implantable-defibrillator pulse detection means defining trigger events upon which ECG data are capture-stored for subsequent playback.
Implantable cardio-verter/defibrillator monitor (ICDM) devices are implanted in the chest cavities of heart patients for automatically pacing and, in the event of fibrillation, stimulating their hearts. Most ICDM devices perform no ECG data monitoring or recording function. The only ones known to do so must compress the ECG data, as storage capacity for ECG data within an implanted device is extremely limited, and/or must telemetrically communicate the ECG data in real time to an external recording device. The most advanced ambulatory ECG data recording and monitoring devices (such as that described in copending U.S. Pat. application Ser. No. 07/321,736, filed March 10, 1989, entitled "Improved Heart Data Monitoring Method and Apparatus", which issued Sept. 25, 1990 as U.S. Pat. No. 4,958,641 having a common assignee herewith), perform no ICDM pulse detection. The only one known to do so continuously monitors both ECG signal and ICDM pulse waveforms for recording them in analogue form on magnetic tape. None of the prior art devices provides long-term monitoring and selective recording of information regarding the pre-ICDM pulse condition that led to the production of a pulse by the ICDM device and the post-ICDM pulse cardiac response thereto.
Accordingly, it is a primary object of this invention to provide an ambulatory heart data monitoring and recording device capable of continuously monitoring and selectively recording ECG data based upon the monitoring of ICDM, or defibrillation, pulses.
Another object of the invention is to provide an ambulatory ECG data monitoring and recording device with ICDM pulse detection means for triggering the capture of ECG data related in time to the occurrence of the ICDM pulse.
Yet another object is to provide ambulatory apparatus having limited memory capacity with the capability of recording selectively ICDM pulse-pertinent ECG data over a long-term recording and monitoring session.
Still another important object of the invention is to provide for the monitoring and recording of ECG data and the detection of ICDM pulses by the use of a single pair of skin electrodes.
Another object is to provide a method of capturing ECG data based upon the occurrence of a ICDM pulse in such manner that the data and the occurrence are relatable in time, thereby facilitating diagnosis of the patient's pre- and post-ICDM pulse cardiac condition.
It is also an object of the invention to provide such method and apparatus in a lightweight, durable, low-cost product that is simple to use and which imposes few restrictions upon the ambulatory patient.
These and other objects of the invention will be understood in reference to the following detailed description of the preferred embodiment and method of the invention, and by reference to the accompanying drawings.